In ruling DOMA unconstitutional partly because it intrudes on what he calls the states’ "exclusive" authority to define marriage, Tauro glosses over an issue with which the federal government was obsessed for most of the 19th Century and even part of the 20th: polygamy, particularly as practiced by Mormons in the western territories.

Tauro notes, accurately enough, that Congress historically deferred to state laws regarding common law marriage and divorce, as well as restrictions regarding interracial marriage, "hygiene," and age at marriage -- despite often-furious controversies.

But Mormon polygamy, like southern slavery, converted the territories into an arena of national moral conflict that inescapably involved all three branches of the federal government -- beginning with President James Buchanan’s ill-fated dispatch of U.S. troops to install a non-Mormon governor in the Utah Territory in 1857.

During the 1856 presidential campaign, the Republican Party platform had accused the Democrats of countenancing "those twin relics of barbarism--polygamy and slavery" and declared it the "duty of Congress to prohibit" both evils in the territories. Buchanan’s expedition was intended to prove the Republicans wrong. It succeeded only in provoking a few inconsequential clashes between armed Mormons and U.S. soldiers.

Congress subsequently adopted three increasingly harsh criminal bans on bigamy and polygamy in the territories: in 1862, 1882 and 1887. The Supreme Court upheldthese laws repeatedly against Mormon challenges alleging, among other things, that they violated religious liberty. The 1887 law, the Edmunds-Tucker Act, abrogated the Mormon Church’s corporate charter and confiscated its property, on the grounds that its leaders encouraged polygamy.

The Supreme Court said that was okay, too. Echoing the majority opinion of the day, the court recoiled in frank horror at a practice the Mormons believed was ordained by God -- but which the justices considered a "crime against the laws and abhorrent to the sentiments and feelings of the civilized world." They compared it to human sacrifice.

Polygamy was the main reason that Congress denied the Utah territorial legislature’s repeated requests for admission as a state.

Finally, in September 1890, the Mormons yielded. Their leader, Wilford Woodruff, decreed: "my advice to the Latter-day Saints is to refrain from contracting any marriage forbidden by the law of the land."

This cleared the way for Utah to become a state in 1896 – on Congress’s terms. Specifically, the Utah Enabling Act said the state could enter the Union as long as its new constitution banned polygamy or plural marriage "forever," and provided that this rule could not be revoked without the consent of the federal government.

So it is a bit misleading to say, as Tauro does, "every [historical] effort to establish a national definition of marriage met failure." Washington’s triumph over Mormon polygamy, made permanent in a national statute, would seem to qualify as a federal definition of marriage, at least in the sense of what marriage is not.

To be sure, Tauro emphasizes that the states have always had exclusive authority over marriage. Utah was a territory at the time of Washington’s effort to stamp out polygamy, and the constitution gave the federal government paramount authority over territories, including their domestic legislation. (That is why, technically, the anti-polygamy laws aimed at Utah also applied to Arizona, Oklahoma, Alaska and the District of Columbia.) Congress functioned, in effect, as the super-legislature for each territory.

Yet what is noteworthy about the Utah case is that Congress leveraged its power over Utah the territory into power over Utah the state. As a condition of admission to the Union, Utah’s people gave Congress a permanent veto over their marriage laws – a veto that remains on the books to this day. The fact that today’s Mormons are proponents of heterosexual monogamy and opponents of same-sex monogamy, is deeply ironic, but legally irrelevant.

What’s more, Utah is not the only state in which this situation obtains. The language of the Utah Enabling Act was repeated, word-for-word, in the laws that admitted New Mexico, Arizona and Oklahoma as states in the early 20th Century. In short, the federal government has shared authority over the marriage laws of four U.S. states.

So it is not quite correct to say, as Tauro does, that "DOMA marks the first time that the federal government has ever attempted to legislatively mandate a uniform federal definition of marriage – or any other core concept of domestic relations, for that matter," or that "as of 1996 the status quo at the federal level was to recognize, for federal purposes, any marriage declared valid according to state law."

In fairness to the judge, the Justice Department seems not to have presented these facts to the court, and they aren’t mentioned in the only historical document in the record before him, an affidavit from Harvard historian Nancy Cott from which Tauro quotes frequently. Maybe we’ll hear more about them if the Obama administration decides to appeal.